Low profile evaporative cooler

ABSTRACT

An evaporative cooler assembly includes a plurality of tubes extending from a refrigerant tank in a spaced relationship to one another with each tube defining a wet air passage. Each pair of adjacent tubes defines a dry air passage extending transversely to the tubes. Each tube includes a plurality of orifices each in fluid communication with the corresponding wet air passage and the adjacent dry air passage. A pair of air ducts are disposed on the refrigerant tank with the tubes being disposed between the air ducts and the air ducts being in fluid communication with the dry air passages whereby a dry air stream flows sequentially through a portion of the dry air passages and into one of the air ducts and through another portion of the dry air passages and into the other air duct until the dry air stream flows out of a dry air outlet as conditioned air.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The subject invention relates to conditioning air, and morespecifically, to conditioning air using the principles of evaporativecooling.

2. Description of the Prior Art

It is known to cool air by flowing the air over an evaporator comprisinga set of tubes carrying a refrigerant. The heat is transferred from theair to the refrigerant flowing within the tubes to cool the air. Therefrigerant then passes through a compressor and is compressed into asuperheated vapor. The heat must then be dissipated from the superheatedrefrigerant vapor before the refrigerant can be used to cool additionalair. Typically, the heat is dissipated into the atmosphere bytransferring the heat from the superheated refrigerant vapor to ambientair flowing over a condenser comprising a set of condensing tubescarrying the superheated refrigerant vapor. As the refrigerant cools, itcondenses back into a liquid.

A significant drawback to the system as described above is therequirement of a chemical refrigerant and a compressor. Chemicalrefrigerants generally are not environmentally friendly, and compressorsconsume energy and tend to make the systems bulky. Accordingly, systemsthat do not require a chemical refrigerant or a compressor have beendeveloped. An example of such a system is a heat and mass exchanger asdisclosed in U.S. patent application No. 11/801,545. The heat and massexchanger as disclosed by Bhatti et al. comprises a refrigerant tankhaving a top surface and defining a refrigerant cavity for housing arefrigerant. The top surface of the refrigerant tank defines a pluralityof tube slots. A plurality of tubes each defining a wet air passageextend between a refrigerant inlet end and a wet air outlet end forproducing a wet air stream. Each of the tubes extend from one of thetube slots and transversely to the refrigerant tank in a spacedrelationship to one another with the wet air passages being in fluidcommunication with the refrigerant cavity. A plurality of cooling finsextending between adjacent tubes to define a plurality of dry airpassages extending transversely to the tubes for receiving a dry airstream. Each of the tubes includes a plurality of orifices each in fluidcommunication with the corresponding wet air passage and the adjacentdry air passage. In operation, a dry air stream is flowed into the dryair passages whereby a portion of the dry air stream is diverted throughthe orifices and into the wet air passages. The wet air stream is cooledby the refrigerant, generally water, in the refrigerant cavity therebydissipating heat from the dry air stream in the dry air passages. Thewet air stream is expelled from the wet air outlet end of each tube asexhaust, and the dry air stream is output from the dry air passages asdry, conditioned air.

While the heat and mass exchanger as disclosed by Bhatti et al.effectively eliminates the need for a chemical refrigerant and acompressor, it tends to be bulky in order to provided the requiredamount of conditioning. Accordingly, there remains a need for a moreefficient evaporative cooler assembly.

SUMMARY OF THE INVENTION

The present invention provides for such an evaporative cooler assemblyimproved by disposing a first air duct defining a first duct passage onthe top surface of the refrigerant tank and adjacent the tubes with thefirst duct passage being in fluid communication with the dry airpassages for receiving the dry air stream. In operation, the dry airstream flows through a first portion of the dry air passages and intothe first duct passage defined by the first air duct and is deflected bythe first air duct into a second portion of the dry air passages to beoutput as conditioned air.

The present invention improves upon the prior art by flowing the dry airstream through the dry air passages a plurality of times. Accordingly,an evaporative cooler having a lower profile can more efficientlycondition the dry air stream.

BRIEF DESCRIPTION OF THE DRAWINGS

Advantages of the present invention will be readily appreciated, as thesame becomes better understood by reference to the following detaileddescription when considered in connection with the accompanying drawingswherein:

FIG. 1 is a perspective and cross-sectional view of an evaporativecooler assembly;

FIG. 2 is a perspective and exploded view of an evaporative coolerassembly; and

FIG. 3 is a fragmentary view of an evaporative cooler assembly.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

Referring to the Figures, wherein like numerals indicate correspondingparts throughout the several views, an evaporative cooler assembly 20for conditioning air is shown generally.

The assembly 20 includes a refrigerant tank 22 having a top surface 24extending between a pair of tank ends 26. The refrigerant tank 22defines a refrigerant cavity 28 for housing a refrigerant, and generallyhas a rectangular cross-section. The refrigerant is preferably water,however, those skilled in the art appreciate other refrigerants can alsobe used. The top surface 24 of the refrigerant tank 22 defines aplurality of tube slots 30. The tube slots 30 are preferably spacedaxially along the top surface 24 of the refrigerant tank 22 between thetank ends 26. The tube slots 30 are generally rectangular for receivinga plurality of generally rectangular tubes 32, however, those skilled inthe art appreciate tube slots 30 of different shapes can also be used.

The plurality of tubes 32 each have an interior surface 34 and aregenerally rectangular in cross-section for being received by the tubeslots 30. Each tube 32 defines a wet air passage 36 extending between arefrigerant inlet end 38 and a wet air outlet end 40 for producing a wetair stream. In an embodiment of the assembly 20, the refrigerant inletend 38 of each tube 32 is disposed in the refrigerant cavity 28 forcontacting the refrigerant, and each of the tubes 32 extend through oneof the tube slots 30 in a spaced relationship to one another with thewet air passages 36 being in fluid communication with the refrigerantcavity 28. In another embodiment of the assembly 20, the refrigerantinlet end 38 of each tube 32 is disposed on the top surface 24 of therefrigerant tank 22 with each wet air passage 36 aligned with one of thetube slots 30 and the tubes 32 extending from the tube slots 30 in aspace relationship to one another with the wet air passages 36 being influid communication with the refrigerant cavity 28. The tubes 32preferably extend in a parallel relationship to one another andperpendicularly from the refrigerant tank 22. Each of the tubes 32 alsopreferably include at least one divider 42 extending between therefrigerant inlet end 38 and the wet air outlet end 40 to define aplurality of the wet air passages 36 and for reinforcing the tube 32.

A wicking material 44 is generally disposed on the interior surface 34of each of the tubes 32 and on each divider 42 for conveying refrigerantfrom the refrigerant cavity 28 into the tubes 32. Additionally, in theembodiment of the assembly 20 wherein each refrigerant inlet end 38 isdisposed on the top surface 24 of the refrigerant tank 22, the wickingmaterial 44 is also preferably disposed on the interior surface of therefrigerant tank 22 for conveying the refrigerant from the refrigerantcavity 28 to the tubes 32.

A plurality of cooling fins 46 extend between adjacent tubes 32 todefine a plurality of dry air passages 48 for receiving a dry air streamand for transferring heat from the dry air stream to the tubes 32. Thedry air passages 48 generally extend transversely to the tubes 32 andare preferably parallel to the tank ends 26. While the cooling fins 46are shown as serpentine fins in the Figures, those skilled in the artappreciate additional types of cooling fins can also be used.

Each of the tubes 32 define a plurality of orifices 50 in fluidcommunication with the corresponding wet air passages 36 and theadjacent dry air passages 48 for diverting a portion of the dry airstream from the dry air passages 48 to the wet air passages 36 forproducing the wet air stream. The orifices 50 are shown in the Figuresas being circular, however, those skilled in the art appreciate thatorifices 50 having a different shape can also be used.

A plurality of top plates 52 each extend between the wet air outlet ends40 of adjacent tubes 32. The top plates 52 define a portion of the dryair passages 48 and add structural support to the assembly 20.

A first air duct 54 defining a first duct passage 56 is disposed on thetop surface 24 of the refrigerant tank 22 and adjacent the tubes 32 withthe first duct passage 56 being in fluid communication with the dry airpassages 48 for receiving the dry air stream. The first air duct 56generally receives the dry air stream from a portion of the dry airpassages 48 and deflects the dry air stream into another, adjacentportion of the dry air passages 48. In an embodiment of the assembly 20as shown in FIG. 1, a second air duct 58 defining a second duct passage60 is disposed on the top surface 24 of the refrigerant tank 22 andadjacent the tubes 32 with the tubes 32 being disposed between the airducts and the second duct passage 60 being in fluid communication withthe dry air passages 48 for receiving the dry air stream that isdeflected by the first air duct 54 into another, adjacent portion of thedry air passages 48. The first and second air ducts are shown in theFigures as having rectangular cross-sections, however, those skilled inthe art appreciate air ducts having different cross-sections can also beused.

A plurality of flow separators 62 are spaced axially along the topsurface 24 of the refrigerant tank 22 and disposed alternately in theair ducts as shown in FIG. 1 for diverting the dry air stream in the airducts. The flow separators 62 are spaced axially along the top surface24 of the refrigerant tank 22 and disposed alternately in the air ductsfor causing the dry air stream to sequentially wind from one of the airducts to a portion of the dry air passages 48 to the other of the airducts to another, adjacent portion of the dry air passages 48.

In an embodiment of the assembly 20 as shown in FIG. 1, one of the airducts is spaced from each of the tank ends 26 to define a dry air inlet64 and a dry air outlet 66. In an alternative embodiment of the assembly20, one of the air ducts defines a dry air inlet 64 and the other of theair ducts defines a dry air outlet 66.

In operation, the dry air inlet 64 receives a dry air stream. The dryair stream flows into a portion of the dry air passages 48, and aportion of the dry air stream is diverted through the orifices 50 of thetubes 32 adjacent the portion of the dry air passages 48 and into thewet air passages 36 defined by the tubes 32 adjacent the portion of thedry air passages 48 to form a wet air stream. The wicking material 44 inthe tubes 32 adjacent the portion of the dry air passages 48 wicks therefrigerant from the refrigerant cavity 28 and into the wet air passages36 defined by the tubes 32. The wet air stream flows over therefrigerant causing the refrigerant to evaporate thereby dissipatingheat from the dry air stream in the dry air passages 48. The wet airstream is output through the wet air outlet ends 40 of each of the tubes32 as exhaust, and the dry air stream flows into one of the air ducts.The dry air stream flows through the corresponding duct passage 56, 60and is deflected by one of the flow separators 62 disposed in thecorresponding air duct 54, 58 and through another, adjacent portion ofthe dry air passages 48 and into the other of the duct passages definedby the other of the air ducts. The dry air passage 48 is then deflectedby one of the flow separators 62 disposed in the other of the air ducts.The dry air stream continues flowing between the air ducts and throughthe dry air passages 48 until the dry air stream reaches the dry airoutlet 66. The lowest temperature of the dry air stream leaving theevaporative cooling assembly 20 equals the dew point temperature of theincoming ambient air (T_(dpi)) defined by the equation:

$\begin{matrix}{T_{dpi} = {T_{wt}\left\{ {1 - {\frac{1}{\alpha}{\ln \left\lbrack \frac{\left( {P_{a}/P_{wt}} \right)\omega_{i}}{\omega_{i} + \left( {M_{w}/M_{a}} \right)} \right\rbrack}}} \right\}^{{- 3}/4}}} & (1)\end{matrix}$

wherein:

-   -   T_(wt) is the triple-point temperature of water=491.6880° R;    -   α is the dimensionless constant for water=15.0197;    -   P_(a) is the atmospheric pressure=14.696 psia;    -   P_(wt) is the triple-point pressure of water=0.088663 psia;    -   ω_(i) is the absolute humidity of the incoming ambient air into        the evaporative cooler assembly 20;    -   M_(w) is the molecular weight of water=18.0152 lb/lb-mole; and    -   M_(a) is the molecular weight of air=28.9645 lb/lb-mole.

The absolute humidity of the incoming ambient air (ω_(i)) into theevaporative cooler assembly 20 is further defined by the equation:

$\begin{matrix}{\omega_{i} = \frac{\left( {M_{w}/M_{a}} \right)\varphi_{i}}{\left( {P_{a}/P_{wi}} \right) - \varphi_{i}}} & (2)\end{matrix}$

wherein:

-   -   φ_(i) is the relative of the incoming ambient air into the        evaporative cooler assembly 20; and    -   P_(wi) is the vapor pressure of water in the incoming ambient        air into the evaporative cooler assembly 20; it is defined by        the equation:

$\begin{matrix}{P_{wi} = {P_{wt}\exp \left\{ {\alpha \left\lbrack {1 - \left( \frac{T_{wt}}{T_{i}} \right)^{4/3}} \right\rbrack} \right\}}} & (3)\end{matrix}$

wherein:

-   -   T_(i) is the dry bulb temperature of the incoming ambient air        into the evaporative cooler assembly 20.

Additionally, the temperature of the wet air stream (T_(wo)) of theevaporative cooler assembly 20 is defined by the equation:

$\begin{matrix}{T_{wo} = {T_{i} - {\frac{1}{2}\left( {A + \sqrt{\left( {A^{2} + {4B}} \right)}} \right)}}} & (4)\end{matrix}$

wherein A and B are the constraints dependent on the psychrometricparameters as defined by the equations below:

$\begin{matrix}{A = \frac{\begin{matrix}{{\left( \frac{{\overset{.}{m}}_{da}}{{\overset{.}{m}}_{wa}} \right)\left( {c_{fw} - c_{pw}} \right)\left( {T_{i} - T_{dpi}} \right)} - {c_{pw}T_{i}} +} \\{{c_{fw}\left( {T_{i} - T_{fpw}} \right)} - {{\beta \left( {1 - \frac{T_{i}}{T_{c}}} \right)}^{3/8}\left( {1 + \frac{\omega_{i}c_{pw}}{c_{pa}}} \right)} - h_{gwi}}\end{matrix}}{c_{fw} - c_{pw}}} & (5)\end{matrix}$

wherein:

-   -   {dot over (m)}_(da) is the mass flow rate of the dry air stream        through the evaporative cooler assembly 20;    -   {dot over (m)}_(wa) is the mass flow rate of the wet air stream        through the evaporative cooler assembly 20;    -   c_(fw) is the specific heat of liquid water=1 Btu/lb ° F.;    -   c_(pw) is the isobaric specific heat of water vapor=0.444 Btu/lb        ° F.;    -   T_(fpw) is the normal freezing point of water=32° F.;    -   β is the constant for water=1339.2 Btu/lb;    -   T_(c) is the critical temperature of water=1165.11° R;    -   c_(pa) is the isobaric specific heat of air=0.240 Btu/lb ° F and    -   h_(gwi) is the specific enthalpy of water vapor at 0° F.=1061        Btu/lb.

The constant B is further defined by the equation:

$\begin{matrix}{B = \frac{\left( {{\overset{.}{m}}_{da}/{\overset{.}{m}}_{wa}} \right)\left( {T_{i} - T_{dpi}} \right)\left\lfloor {{c_{pw}T_{i}} - {c_{fw}\left( {T_{i} - T_{fpw}} \right)} + h_{gwi}} \right\rfloor}{c_{fw} - c_{pw}}} & (6)\end{matrix}$

and the ratio of absolute humidity ω_(wo) of wet air stream leaving theevaporative cooler assembly 20 to the absolute humidity ω_(i) of theambient air stream entering the evaporative cooler assembly 20 isfurther defined by the equation:

$\begin{matrix}{\frac{\omega_{wo}}{\omega_{i}} = {1 + \frac{\left( {c_{pw} + {c_{pa}/\omega_{i}}} \right)\left( {T_{i} - T_{wo}} \right)}{h_{gwi} + {c_{pw}T_{wi}} - {c_{fw}\left( {T_{wo} - T_{fpw}} \right)}}}} & (7)\end{matrix}$

wherein all the symbols have been previously defined.

While the invention has been described with reference to an exemplaryembodiment, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing from theessential scope thereof. Therefore, it is intended that the inventionnot be limited to the particular embodiment disclosed as the best modecontemplated for carrying out this invention, but that the inventionwill include all embodiments falling within the scope of the appendedclaims.

1. An evaporative cooler assembly for conditioning air comprising: arefrigerant tank having a top surface and defining a refrigerant cavityfor housing a refrigerant; said top surface of said refrigerant tankdefining a plurality of tube slots; a plurality of tubes each defining awet air passage extending between a refrigerant inlet end and a wet airoutlet end for producing a wet air stream; each of said tubes extendingfrom one of said tube slots and transversely to said refrigerant tank ina spaced relationship to one another with said wet air passages being influid communication with said refrigerant cavity; each pair of adjacenttubes defining a dry air passage extending transversely to said tubesfor receiving a dry air stream; each of said tubes including a pluralityof orifices in fluid communication with said corresponding wet airpassage and said adjacent dry air passage for diverting a portion of thedry air stream from said dry air passage to said wet air passage forproducing the wet air stream; and a first air duct defining a first ductpassage disposed on said top surface of said refrigerant tank andadjacent said tubes with said first duct passage being in fluidcommunication with said dry air, passages for receiving the dry airstream; whereby the dry air stream flows through a first portion of saiddry air passages and into said first duct passage defined by said firstair duct and is deflected by said first air duct into a second portionof said dry air passages to be output as conditioned air.
 2. Theassembly as set forth in claim 1 including a second air duct defining asecond duct passage disposed on said top surface of said refrigeranttank and adjacent said tubes with said tubes being disposed between saidair ducts and said second duct passage being in fluid communication withsaid dry air passages for receiving the dry air stream.
 3. The assemblyas set forth in claim 2 including a plurality of flow separators beingspaced axially along said top surface of said refrigerant tank anddisposed alternately in said air ducts for diverting the dry air streamin said air ducts whereby the dry air stream sequentially flows througha portion of said dry air passages and into one of said-duct passagesdefined by said corresponding air duct and is deflected by one of saidflow separators disposed in said corresponding air duct and throughanother portion of said dry air passages and into the other of said ductpassages defined by the other of said air ducts and is deflected by oneof said flow separators disposed in the other of said air ducts.
 4. Theassembly as set forth in claim 3 wherein said refrigerant tank extendsbetween a pair of tank ends and one of said air ducts is spaced fromeach of said tank ends to define a dry air inlet and a dry air outlet.5. The assembly as set forth in claim 3 wherein one of said air ductsdefines a dry air inlet and the other of said air ducts defines a dryair outlet.
 6. The assembly as set forth in claim 3 including aplurality of cooling fins extending between adjacent tubes to define aplurality of said dry air passages extending transversely to said tubesbetween said adjacent tubes for receiving the dry air stream.
 7. Theassembly as set forth in claim 3 wherein said refrigerant inlet end ofeach tube is disposed in said refrigerant cavity for contacting therefrigerant and each of said tubes extends through one of said tubeslots.
 8. The assembly as set forth in claim 3 wherein said tubes extendperpendicularly to said refrigerant tank.
 9. The assembly as set forthin claim 3 wherein said tubes extend in a parallel relationship.
 10. Theassembly as set forth in claim 3 wherein said refrigerant tank extendsbetween a pair of tank ends and said dry air passages extend parallel tosaid tank ends.
 11. The assembly as set forth in claim 3 wherein each ofsaid tubes have an interior surface and including a wicking materialdisposed on said interior surface of each of said tubes for conveyingrefrigerant from said refrigerant cavity into said tubes.
 12. Theassembly as set forth in claim 3 wherein each of said tubes include atleast one divider extending between said refrigerant inlet end and saidwet air outlet end to define a plurality of said wet air passages andfor reinforcing said tube.
 13. The assembly as set forth in claim 12including a wicking material disposed on said dividers of each of saidtubes for conveying refrigerant from said refrigerant cavity into saidtubes.
 14. The assembly as set forth in claim 3 wherein said tube slotsare spaced axially along said top surface of said refrigerant tank. 15.The assembly as set forth in claim 3 including a plurality of top plateseach extending between said wet air outlet ends of adjacent tubes. 16.The assembly as set forth in claim 3 wherein said tubes are generallyrectangular in cross-section and said tube slots are generallyrectangular.
 17. The assembly as set forth in claim 3 wherein saidrefrigerant tank has a rectangular cross-section.
 18. An evaporativecooler assembly for conditioning air comprising: a refrigerant tankhaving a top surface extending between a pair of tank ends and arectangular cross-section and defining a refrigerant cavity for housinga refrigerant; said top surface of said refrigerant tank defining aplurality of tube slots being generally rectangular and spaced axiallyalong said top surface of said refrigerant tank between said tank ends;a plurality of tubes each having an interior surface and a generallyrectangular cross-section and defining a wet air passage extendingbetween a refrigerant inlet end and a wet air outlet end for producing awet air stream, said refrigerant inlet end of each tube disposed in saidrefrigerant cavity for contacting said refrigerant; each of said tubesextending through one of said tube slots and perpendicularly to saidrefrigerant tank in a spaced and parallel relationship to one anotherwith said wet air passages being in fluid communication with saidrefrigerant cavity; each of said tubes including at least one dividerextending between said refrigerant inlet end and said wet air outlet endto define a plurality of said wet air passages and for reinforcing saidtube; a wicking material disposed on said interior surface and saiddividers of each of said tubes for conveying refrigerant from saidrefrigerant cavity into said tubes; a plurality of cooling finsextending between adjacent tubes to define a plurality of dry airpassages extending transversely to said tubes and parallel to said tankends for receiving a dry air stream and for transferring heat from thedry air stream to said tubes; a plurality of top plates each extendingbetween said wet air outlet ends of adjacent tubes; each of said tubesdefining a plurality of orifices in fluid communication with saidcorresponding wet air passages and said adjacent dry air passages fordiverting a portion of the dry air stream from said dry air passages tosaid wet air passages for producing the wet air stream; a first air ductdefining a first duct passage disposed on said top surface of saidrefrigerant tank and adjacent said tubes with said first duct passagebeing in fluid communication with said dry air passages for receivingthe dry air stream; a second air duct defining a second duct passagedisposed on said top surface of said refrigerant tank and adjacent saidtubes with said tubes being disposed between said air ducts and saidsecond duct passage being in fluid communication with said dry airpassages for receiving the dry air stream; a plurality of flowseparators being spaced axially along said top surface of saidrefrigerant tank and disposed alternately in said air ducts fordiverting the dry air stream in said air ducts; and one of said airducts being spaced from each of said tank ends to define a dry air inletand a dry air outlet; whereby the dry air stream flows through said dryair inlet and sequentially through a portion of said dry air passagesand into one of said duct passages defined by said corresponding airduct and is deflected by one of said flow separators disposed in saidcorresponding air duct and through another portion of said dry airpassages and into the other of said duct passages defined by the otherof said air ducts and is deflected by one of said flow separatorsdisposed in the other of said air ducts until the dry air stream flowsout of said dry air outlet as conditioned air.